Mahmoud Hrouk's sobbing mother baffled as to why he was murdered in such an 'inhumane' way

The mother of 16-year-old Mahmoud Hrouk says she still has no idea why her "angel" was murdered by an acquaintance in such an "inhumane" way.

Aymen Terkmani, 24, refused to look at Maha Dunia as she sobbed through a victim impact statement at his sentence hearing, more than two years after he killed the teenager at Fairfield East.

"I am not sure of why the murderer inflicted so much harm on him or why you wanted my innocent son dead” she sobbed.

"It's hard for me to understand how a human can be capable of what he did to my son.”

Mahmoud Hrouk's mother Maha Dunia said her life had been cut short as well as her son's. ()The attack on Mahmoud Hrouk, 16, was described by prosecutors as "horribly vicious". (Facebook)Aymen Terkmani arriving for his sentencing hearing today. (9NEWS) ()

Mrs Dunia also described her struggle to function every day since her son’s death and said her life had been cut short as well.

"Never in my life will he ever turn home not to hold me, not hug me, not to annoy me or even just to look at me.”

It was the 16th of May 2015 when the teenager failed to return home, and his worried parents called repeatedly demanding he come home.